Field of the Invention
This invention relates to an interconnection for battery pack protection.
Introduction to the Invention
Electronic equipment such as notebook or laptop computers or tablets often contains multiple battery cells, or battery packs containing multiple cells, connected to one another as a means to provide adequate energy for laptop computers, tablets, and other electronic devices. Lithium-ion and lithium-polymer batteries (collectively “Li-batteries”) are often used due to their high energy density, small form factors and design flexibility. However, Li-battery packs are sensitive to faults caused by external shorts, runaway charging conditions and/or abusive overcharging that can result in potentially damaging overcurrent and overtemperature conditions. The overcharge, deep-discharge, or short circuit conditions that create heat can cause a Li-battery cell to bloat, rupture, or experience other issues. Thus, it is necessary that the cells, whether individually or connected as a pack, be protected, e.g. by means of a thermal cutoff (TCO) device or other type of overcurrent and overtemperature device, that interrupts current in order to help prevent damage in the event of an overcurrent and/or overtemperature situation.
Protection devices such as positive temperature coefficient (PTC) devices and TCOs can be connected to the battery cell or pack in any manner, e.g. in series, in parallel, or any combination thereof, that allows appropriate protection. However, the arrangement of the batteries in the electrical equipment is subject to constraints such as space, which is a particular issue as electronic equipment becomes smaller and thinner. In addition, ease of connection and assembly is required. A conventional method of arranging batteries is to align the positive electrode in the first of a pair of battery cells with the negative electrode in the second of the pair, and to make a connection to the protection device(s) and from one positive electrode to a second positive electrode, and from one negative electrode to a second negative electrode, by means of wires. Such wires must be soldered or welded to the various components in the circuit, and the installation can result in a disordered and/or cluttered wiring arrangement. The complicated arrangement may have a conductive path with a long length which will have higher power dissipation, higher resistance, and higher voltage drop. All of these could result in the electronic equipment overheating. Furthermore, the arrangement takes up valuable space in the equipment, sometimes resulting in a larger device size to accommodate the protection devices and the wiring. Simplifying the arrangement while still providing adequate protection is thus desired.